Clearness, the message should be clear; and based on simple terms. Have a definite purpose for writing and make sure it is clearly communicated up front. The content should be meaningful to the receiver and be compatible with his or her values system.
Consideration, the capability of the audience should be considered. The most effective communications require the least amount of the recipient's effort. Keep your reader's needs in mind as you write. Ask yourself, why should my reader spend time reading this? So make it worthwhile for them.
Completness is the way that you convey your message in a effective way so that the that reader easily urderstands it so that he/she reacts in the way that you would expect him to.
Conciseness is being able to keep to your point and don't give too much detail, which is unneccessary.
Cosideration is that you put yourself in the place of the receiver when you are composing a message.